Good keeping quality under various conditions is required of color photographic images formed by the oxidative coupling of dye image-forming couplers (which are abbreviated as couplers, hereinafter) with a color developing agent. In effecting an improvement in keeping quality, it is necessary to ensure that developed color images differing in hue become discolored or change their colors at the lowest possible speed, and also to ensure that the images are of nearly equal discoloring speed over the whole density range, that is to say, to ensure that color balance remains unaltered among the dye images even after the lapse of a long period of time.
However, conventional photographic materials, particularly color paper, are subject to change in color balance since cyan dye images deteriorate to a great extent through long range dark discoloration due to the influences of moisture and heat thereon. Therefore, it is strongly desired to minimize such a change.
In Japanese Patent Application (OPI) Nos. 80045/81 (corresponding to U.S. Pat. No. 4,334,011) and 10433/81 (corresponding to U.S. Pat. No. 4,327,173) (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"), Japanese Patent Publication No. 37857/82 (corresponding to U.S. Pat. No. 4,333,999), Japanese Patent Application (OPI) Nos. 105229/83 (corresponding to U.S. Pat. No. 4,430,423) and 24547/85 (corresponding to U.S. Pat. No. 4,565,777), and so on, it is stated that phenol type couplers in which the benzene ring is substituted by acylamino groups at the 2- and 5-positions (so-called 2,5-diacylaminophenol type couplers) have decided superiority in fastness of cyan dye images produced therefrom, that is to say, the described phenol type couplers offer the possibility of solving the above-described problem.
As reported therein, 2,5-diacylaminophenol type couplers are very useful couplers for the production of color photographic images having good keeping quality, especially high fastness to heat. Moreover, photographic materials prepared using such couplers are known to possess excellent processing stability, and particularly, are known to suffer little from a lowering of cyan density at the stage of bleach-fix processing. Namely, they are excellent in color restoration also.
As described above, 2,5-diacylaminophenol type couplers are preferred as cyan dye-forming couplers for use in color photographic light-sensitive materials.
However, great difficulties have so far attended the attempts to mass produce photographic lightsensitive materials which have the same quality in each of the products when 2,5-diacylaminophenol type couplers are incorporated into the light-sensitive material. This is because what grade of photographic properties the resulting photographic material can have depends largely upon the time elapsed from the preparation of an emulsion containing a 2,5-diacylaminophenol type coupler until the coating of the emulsion. In equipment for mass producing a photographic light-sensitive material, it is difficult to achieve equalization of the time elapsed from the preparation of each emulsion to be coated until the coating of the emulsion on a support. Such a fluctuation in photographic properties resulting from 2,5-diacylaminophenol type couplers are a serious obstacle to mass production of a photographic light-sensitive material having standardized properties. It has been known that the influence of 2,5-diacylaminophenol type couplers on an adsorbed condition of spectral sensitizing dyes at the individual surfaces of silver halide grains is responsible for the variation of photographic properties which depends on the time elapsed until the prescribed emulsion is coated. As a means of solving the above-described problem, therefore, it has been proposed to employ spectral sensitizing dyes of the kind which are hardly affected or influenced by the 2,5-diacylaminophenol type coupler upon their adsorbed condition. Such a means is embodied, e.g., in Japanese Patent Application (OPI) Nos. 166955/84 and 214030/84.
However, it is, in general, considerably difficult from the practical point of view, as described below, to select such a sensitizing dye as not to cause any fluctuations in photographic properties in the case where a photographic light-sensitive material is mass produced utilizing a 2,5-diacylaminophenol type coupler.
This is because photographic properties affected by spectral sensitizing dyes are not confined to fundamental ones including spectral sensitizing strength and wavelength region, but their influences extend to multifarious photographic properties, such as illumination dependence of the sensitivity of photographic emulsions, keeping quality of latent images, freshness keeping capability under long range storage, and so on. Therefore, sensitizing dyes which are hardly affected or influenced by 2,5-diacylaminophenol type couplers present therewith can not always contribute to all of the above-described photographic properties to a satisfactory extent.
Under these circumstances, it may safely be said that the fluctuation in photographic properties due to 2,5-diacylaminophenol type couplers is still a great obstacle when the contribution of spectral sensitizing dyes to photographic properties is considered.